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Part of the company’s FS FUNCTIONAL SAFETY SERIES, the STA is certified to IEC 61508: Parts 1, 2 and 3 by TÜV Rheinland for single use in Safety Instrumented Systems up to SIL 2. The STA firmware is suitable for a SIL 3 system, which allows the STA to be used in a redundant architecture (1oo2, 2oo3, etc.) up to SIL 3.

The 4-wire (line/mains-powered) STA accepts a signal input from transmitters (current and voltage inputs), temperature sensors (RTD and thermocouple inputs), resistance and potentiometer devices, and a wide range of other monitoring and control equipment.

The STA provides three failsafe alarm outputs. Two are configurable process alarms that trip when a monitored process variable falls outside of user-set high and/or low limits. The third alarm is a non-programmable, latching alarm that is activated if any internal faults are found by the STA’s extensive internal diagnostics. This fault relay is also triggered if the input is faulty or broken.

The STA is provided with comprehensive FMEDA (Failure Modes, Effects and Diagnostics Analysis) certified safety data to be used by a competent functional safety practitioner to determine the unit’s applicability as a logic solver in specific safety-related applications.

The STA features industry-best 20-bit input resolution; long term stability of up to 5 years between scheduled calibrations; a rugged, industrial metal housing; and isolation and RFI/EMI protection that provides superior protection against the effects of ground loops, plant noise, and radio frequency and electromagnetic interference. The unit also features standard “transmitter excitation” to provide 24V power to a 2-wire transmitter. The STA Safety Trip Alarm can be ordered with an analog output option (not part of the safety path) to provide a combination alarm trip and transmitter in one compact unit.